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authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2011-05-24 08:31:09 -0700
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2011-09-28 21:36:37 -0700
commitb3fbab0571eb09746cc0283648165ec00efc8eb2 (patch)
tree63bc01cbf03a5df34a96af292a00df4a96dc148a /kernel/sched.c
parentd5988af53102f3b73e5e0788be024ccfa51869de (diff)
downloadlinux-b3fbab0571eb09746cc0283648165ec00efc8eb2.tar.bz2
rcu: Restore checks for blocking in RCU read-side critical sections
Long ago, using TREE_RCU with PREEMPT would result in "scheduling while atomic" diagnostics if you blocked in an RCU read-side critical section. However, PREEMPT now implies TREE_PREEMPT_RCU, which defeats this diagnostic. This commit therefore adds a replacement diagnostic based on PROVE_RCU. Because rcu_lockdep_assert() and lockdep_rcu_dereference() are now being used for things that have nothing to do with rcu_dereference(), rename lockdep_rcu_dereference() to lockdep_rcu_suspicious() and add a third argument that is a string indicating what is suspicious. This third argument is passed in from a new third argument to rcu_lockdep_assert(). Update all calls to rcu_lockdep_assert() to add an informative third argument. Also, add a pair of rcu_lockdep_assert() calls from within rcu_note_context_switch(), one complaining if a context switch occurs in an RCU-bh read-side critical section and another complaining if a context switch occurs in an RCU-sched read-side critical section. These are present only if the PROVE_RCU kernel parameter is enabled. Finally, fix some checkpatch whitespace complaints in lockdep.c. Again, you must enable PROVE_RCU to see these new diagnostics. But you are enabling PROVE_RCU to check out new RCU uses in any case, aren't you? Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'kernel/sched.c')
-rw-r--r--kernel/sched.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/kernel/sched.c b/kernel/sched.c
index ec5f472bc5b9..e24cebe0e6cb 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -4237,6 +4237,7 @@ static inline void schedule_debug(struct task_struct *prev)
*/
if (unlikely(in_atomic_preempt_off() && !prev->exit_state))
__schedule_bug(prev);
+ rcu_sleep_check();
profile_hit(SCHED_PROFILING, __builtin_return_address(0));
@@ -8230,6 +8231,7 @@ void __might_sleep(const char *file, int line, int preempt_offset)
{
static unsigned long prev_jiffy; /* ratelimiting */
+ rcu_sleep_check(); /* WARN_ON_ONCE() by default, no rate limit reqd. */
if ((preempt_count_equals(preempt_offset) && !irqs_disabled()) ||
system_state != SYSTEM_RUNNING || oops_in_progress)
return;